Fixed asset experts : One of my customer needs ability to transfer the fixed asset to their customer while being able to track it, they charge for the time (per hour) but not rent.

create a custom record in NetSuite called "Customer Asset Usage". This record logs the asset, customer, usage dates, and total hours used. Then use a SuiteScript to generate invoices based on this usage data

Is this the only way? Or is this the easier way Or can you do it manually I mean without scripting

Just do not think of this asset as an asset. Think of a product you sell to the customer. that stands if you record your depreciation for this asset as normal, no changes. Just create an item, link an asset to it (can do functionally, there is a filed for that on SO), and track usage (i.e. hours) somehow

We also need to get the item back, it’s not technically sold

right, and that’s why you separate your asset from the sale. I mean nothing changes on your books re: depreciation, right?

a custom record can be useful to track the time used by your client. Regarding the invoice, you can generate it by script or manually. In addition, remember to use a non-inventory item ( on the invoice ) linked to this asset rental to your client