see below... What I am reading is Royalty bearing is not ane time fee... (not an expert but from what I read it seems to be different... Corrections welcome)

What are the considerations in choosing between a royalty-bearing agreement and
a paid-up agreement? If you stand back and look at the business arrangement, you will
soon conclude that if you have a royalty-bearing agreement, you are closely linked to
your licensee's success. In other words, if the licensee makes money, you will receive
royalties and be successful. If the licensee is not successful, you may receive nothing.
On the other hand, in a paid-up license, the licensee has paid you a fixed amount up front.
The licensee is taking all the risks of business, and your only concerns are collateral obligations the licensee might have relative to the licensed technology. Thus, in a
royalty-bearing agreement you are speculating on the business just as the licensee is,
while in a paid-up arrangement the licensor is not speculating and has already been paid
for the license.