Difference gre vs ip-lease


where is the difference between /24 IP network (256 IPv4) for rent from 0,50 € per IPv4 and Rent IPv4 from Germany for 0,50 Euro each IPv4

You need your own ASN for /24. But you don’t need ASN for FlexIPs.

Where can I get an ASN?

You can get from LIRs.

Can you please explain me more? Maybe write a tutorial? And with a ASN I can connect ever server worldwide with leased ip range from noez?

you can apply to get an ASN at RIPE NCC organization. usually you do this via a member of RIPE NCC a so called LIR local internet registry. to have an ASN does not help yet as the main issue is to be able to provide own BGP routing with such ASN autonomous system number (<- your network ID) and to be able to finally route some IPv4 /24 for example.